Genomic Study Traces Bed Bug Evolution Alongside Human Expansion

A recent study led by Virginia Tech researchers compared the whole genome sequences of two genetically distinct bed bug lineages—one associated with humans and the other with bats. Their findings, published in Biology Letters, reveal that bed bugs living with humans have experienced population growth that mirrors the expansion of human populations, while those remaining with bats have continued to decline since the Last Glacial Maximum about 20,000 years ago.

Lead author Lindsay Miles explained, “We wanted to look at changes in effective population size, which is the number of breeding individuals that are contributing to the next generation, because that can tell you what’s been happening in their past.” The research shows that both bed bug populations declined during the ice age. However, only the human-associated lineage recovered, increasing in effective population size as humans formed larger settlements and cities, such as Mesopotamia, around 12,000 years ago.

Warren Booth, senior author of the study, noted, “There were bed bugs living in the caves with these humans, and when they moved out they took a subset of the population with them so there’s less genetic diversity in that human-associated lineage.” As humans expanded into cities, the human-associated bed bugs experienced exponential population growth.

The study also highlights the evolutionary relationship between humans and bed bugs, which could inform models predicting pest and disease spread in urban environments. Researchers are interested in recent evolutionary changes, particularly in the last 100 to 120 years, including the development of insecticide resistance. The team has already identified a gene mutation related to resistance and are using historical and modern samples to investigate further.